The Hebron Project is the fourth major development offshore Newfoundland and Labrador, Canada, with an estimated 2620 million barrels of oil and a target first oil in 2017. The Ben Nevis reservoir accounts for approximately 80% of the crude oil with an estimated 30% recoverable. Hence, enhanced oil recovery (EOR) requires attention now even before production starts. This research evaluates the effectiveness of silicon dioxide (SiO2) nanoparticles as a water additive to enhance oil recovery in the Ben Nevis Formation, Hebron Field. The experiments involved two main steps: measuring interfacial tension, and determining the wetting character of the rock surfaces. Unlike previous research using SiO2 nanoparticles, in this work, the SiO2 nanoparticles are dispersed in seawater instead of deionized water or simple synthetic brine; experiments are conducted at reservoir conditions (Hebron Field: 62°C and 19.00 MPa); and synthetic cores were used that best represented facies of Ben Nevis Formation. A major challenge was forming a stable SiO2 nanofluid in North Atlantic seawater. Since salinity directly affected the stability of the nanofluid, hydrochloric acid was used as a stabilizer. Interfacial tension (IFT) was measured for SiO2 dispersed in deionized water, as well as stable nanofluids with SiO2 concentrations of 0.01, 0.03, and 0.05 wt% dispersed in seawater, to determine the contribution of SiO2 nanoparticle on the alteration of IFT. The contact angles were measured on core plugs before and after aging in 0.01, 0.03, and 0.05 wt% SiO2 nanofluids, to determine whether SiO2 nanoparticles can alter the wettability of the core. The results show that hydrophilic SiO2 nanoparticles are effective water additive for EOR. When comparing IFT experiments with deionized water and SiO2 nanoparticles dispersed in deionized water, the nanoparticles reduced the IFT from 39.70 mN/m to 21.54 mN/m. IFT is also reduced from 21.80 mN/m to 16.61 mN/m in case of experiments in seawater and a 0.05 wt% stable SiO2 nanoparticles dispersed in seawater. The contact angle experiments demonstrate that SiO2 can decrease the contact angle, and therefore make the rock surface more water wet under reservoir conditions. Finally, it is also found that the higher the SiO2 nanoparticle concentration, the higher the wettability alteration.